Water Freezing Prevention In freezing weather conditions, do not allow the water in the SLED modules to freeze to a solid mass of ice. If the temperature at the SLED site is expected to be at or below the freezing point of water 32° F [ 0°C ], it is recommended that an additive be used to prevent the water in the SLED modules from freezing. See Table 1 on pg 17. -Common additives used to prevent water freezing currently used in work zone devices under the same category as the SLED Modules. SALT (Sodium Chloride) 20% mixture by weight Reduces freezing down to 0° F [-18° C]. Corrosive to inadequately protected steel components (Galvanizing adequately prevents corrosion) Recommended - premix before filling Prevent spilling since solution is harmful to vegetation, soils, and wildlife. Draining should be done in an acceptable area. CALCIUM CHLORIDE 35% mixture by weight Reduces Freezing down to 20° F [ -6.6 °C ]. Corrosive to thin zinc plated components Corrosive to inadequately protected steel components (Galvanizing adequately prevents corrosion) High tendency to stay on road surface resulting in slick road surface. High level of heat created when mixing. It is recommended that pre-mixing is done before filling. Prevent spilling since solution is harmful to vegetation, soils, and wildlife. Draining should be done in an acceptable area. ETHYLENE/PROPYLENE GLYCOL 50% mixture by volume Reduces water freezing to 0° F [-18° C]. High tendency to stay on road surface resulting in slick road surface. Prevent spilling since solution is harmful to vegetation, soils, and wildlife. Draining should be done in an acceptable area. LIQUID CMA (Calcium Magnesium Acetate) 25% mixture by volume Reduces water freezing to 0° F [-18° C]. Has a low environmental impact. LIQUID POTASSIUM ACETATE 60% mixture by volume Reduces water freezing to 20° F [-6.6° C] Low corrosive characteristics and has a low environmental impact. Revision C (Dated DRAFT) 14 Table 1- Recommended water freezing prevention chart solution comparison. Environmental Additive Impact Cost Rating Protection Temp Mix Solution Ratio Salt (Sodium Chloride) Harmful Low 0 °F [-18 ° C] 20% by weight Calcium Chloride Harmful Medium 20 °F [-6.6 ° C] 35% by weight Ethylene/Propylene Glycol Dangerous High 0 °F [-18 ° C] 50% by volume Liquid CMA Non-Toxic High 0 °F [-18 ° C] 25% by volume Liquid Potassium Acetate Non-Toxic High 20 °F [-6.6 ° C] 60% by volume Revision C (Dated DRAFT) 15 .